NEC PD78F9488 Manuale Utente

CHAPTER  13   LCD  CONTROLLER/DRIVER 

 

User’s Manual  U15331EJ4V1UD

Figure 13-10 shows how a nine-digit LCD panel having the display pattern shown in Figure 13-9 is connected to 

the segment signals (S0 to S26) and the common signals (COM0 to COM2) of the 

µ

PD789489 Subseries chip.  This 

example displays the data "123456.789" in the LCD panel.  The contents of the display data memory (addresses 
FA00H to FA1AH) correspond to this display. 

The following description focuses on numeral "6." (   ) displayed as the fourth digit from the right.  To display "6." in 

the LCD panel, it is necessary to apply the select or deselect voltage to the S9 to S11 pins according to Table 13-5 at 
the timing of the common signals COM0 to COM2; see Figure 13-9 for the relationship between the segment signals 
and LCD segments. 

 

Segment S9  S10 S11 

Common  

 

 

COM0 Deselect 

Select 

Select 

COM1 Select 

Select 

Select 

COM2 Select 

Select 

− 

 

According to Table 13-5, it is determined that the display data memory location (FA09H) that corresponds to S9 

must contain x110. 

Figure 13-11 shows an example of LCD drive waveforms between the S9 signal and each common signal.  When 

the select voltage is applied to S9 at the timing of COM1 or COM2, an alternate rectangle waveform, +V

LCD

/-V

LCD

, is 

generated to turn on the corresponding LCD segment. 

 

;;

;;

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;;

;

;

;;;

;;;

;;

;;

;;

;;

;;

;;

;;

S

3n+2

S

3n

COM0

COM2

S

3n+1

COM1

 

Remark  n = 0 to 8